Fix inode filtering with multiple devices

Inodes are only unique per device, so include device in the lookup.

Also replace a conditional with an additional pattern match, makes it a
bit tidier I think.

src/inodefilter.rs

@@ -2,23 +2,27 @@ use std::collections::HashMap;
 
 #[derive(Debug, Default, Clone)]
 pub struct InodeFilter {
-    inner: HashMap<u64, u64>,
+    inner: HashMap<(u64, u64), u64>,
 }
 
 impl InodeFilter {
     #[cfg(unix)]
     pub fn add(&mut self, metadata: &std::fs::Metadata) -> bool {
         use std::os::unix::fs::MetadataExt;
 
-        self.add_inode(metadata.ino(), metadata.nlink())
+        self.add_dev_inode((metadata.dev(), metadata.ino()), metadata.nlink())
     }
 
     #[cfg(windows)]
     pub fn add(&mut self, metadata: &std::fs::Metadata) -> bool {
         use std::os::windows::fs::MetadataExt;
 
-        if let (Some(inode), Some(nlinks)) = (metadata.file_index(), metadata.number_of_links()) {
-            self.add_inode(inode, nlinks as u64)
+        if let (Some(dev), Some(inode), Some(nlinks)) = (
+            metadata.volume_serial_number(),
+            metadata.file_index(),
+            metadata.number_of_links(),
+        ) {
+            self.add_dev_inode((dev as u64, inode), nlinks as u64)
         } else {
             true
         }
@@ -29,23 +33,22 @@ impl InodeFilter {
         true
     }
 
-    pub fn add_inode(&mut self, inode: u64, nlinks: u64) -> bool {
+    pub fn add_dev_inode(&mut self, dev_inode: (u64, u64), nlinks: u64) -> bool {
         if nlinks <= 1 {
             return true;
         }
 
-        match self.inner.get_mut(&inode) {
+        match self.inner.get_mut(&dev_inode) {
+            Some(1) => {
+                self.inner.remove(&dev_inode);
+                false
+            }
             Some(count) => {
                 *count -= 1;
-
-                if *count == 0 {
-                    self.inner.remove(&inode);
-                }
-
                 false
             }
             None => {
-                self.inner.insert(inode, nlinks - 1);
+                self.inner.insert(dev_inode, nlinks - 1);
                 true
             }
         }
@@ -60,14 +63,16 @@ mod tests {
     fn it_filters_inodes() {
         let mut inodes = InodeFilter::default();
 
-        assert!(inodes.add_inode(1, 2));
-        assert!(!inodes.add_inode(1, 2));
+        assert!(inodes.add_dev_inode((1, 1), 2));
+        assert!(inodes.add_dev_inode((2, 1), 2));
+        assert!(!inodes.add_dev_inode((1, 1), 2));
+        assert!(!inodes.add_dev_inode((2, 1), 2));
 
-        assert!(inodes.add_inode(1, 3));
-        assert!(!inodes.add_inode(1, 3));
-        assert!(!inodes.add_inode(1, 3));
+        assert!(inodes.add_dev_inode((1, 1), 3));
+        assert!(!inodes.add_dev_inode((1, 1), 3));
+        assert!(!inodes.add_dev_inode((1, 1), 3));
 
-        assert!(inodes.add_inode(1, 1));
-        assert!(inodes.add_inode(1, 1));
+        assert!(inodes.add_dev_inode((1, 1), 1));
+        assert!(inodes.add_dev_inode((1, 1), 1));
     }
 }